FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
AND
THE PATENT RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
“A SYSTEM AND METHODS FOR AVAILING SERVICES
IN AN INTERNATIONAL ROAMING”
We, RELIANCE JIO INFOCOMM LIMITED, an Indian National, of, 3rd Floor, Maker
Chamber‐IV, 222, Nariman Point, Mumbai‐400021, Maharashtra, India.
The following specification particularly describes the invention and the manner in
which it is to be performed.
2
TECHNICAL FIELD
The present disclosure generally relates to mobile communications and is more
specifically, directed to systems and methods for availing services from a foreign
network while a mobile user is in international roaming.
5 BACKGROUND
A subscriber identity module (SIM) configured in a mobile device or a smart
device in the form of a chip card contains essential individual subscriber data
that is required for facilitating mobile services. A typical SIM card comprises an
integrated circuit chip that is intended to securely store the international mobile
10 subscriber identity (IMSI) number and the related key/s, which may be used to
identify and authenticate subscribers/users on the mobile devices along with
other information including, but not limiting to, its unique serial number (ICCID),
international mobile subscriber identity (IMSI) number and security
authentication and ciphering information. SIM cards are typically designed to be
15 transferable between different mobile devices. Further, the SIM circuit forms a
part of the function of a Universal Integrated Circuit Card (UICC) physical smart
card (referred to as ‘SIM’ card herein). Also, the SIM comprises a SIM file system
that further consists of the Master File (MF), Dedicated Files (DFs) and the
Elementary Files (EFs) that are mainly used for controlling the user equipment’s
20 (UE) behaviour in the network by facilitating a secured registration to desired
network, deciding which services should be restricted and allowed and
subsequently maintaining a status list of the EF and DF files.
Further, each subscriber is identified by a unique International Mobile Subscriber
Identity (IMSI) which consists of the PLMN (MCC, MNC) of a network operator
25 and the Mobile Subscription Identification Number (MSIN). There are different
network operators (either available in same country or different country) which
provide such voice and data services to subscribers not only of their own
3
subscribers but also from other networks. Therefore, in an exemplary instance,
of international roaming, when the subscriber (Roaming Subscriber (RS)) leaves
the home network and moves to a foreign location (Roamed Network (RN)), the
user equipment receives services from another network within the same country
due to unavailability 5 of the home network as per bilateral roaming agreements
between the home and the roamed network operators.
In recent years, wireless communication networks have undergone tremendous
growth and commercialization, thereby resulting in increased number of services
and features offered on such devices. Therefore, it has now become essential to
10 provide good quality roaming network for maintaining a network operator’s
brand value for roaming services, since these network operators provide a
plurality of subscribed services to the users/subscribers by facilitating
registration, authentication, location updating, handovers, call routing, etc.
Currently, the wireless networks are being configured to provide an Auto IMSI
15 Switch SIM application in case of international roaming by facilitating swapping
the IMSI (home IMSI) of the home network operator with an IMSI (Global IMSI)
of a global Network Operator. With the updated IMSI, the user equipment may
easily avail services in international roaming. However, there are two
prerequisites for successful functioning of the Auto IMSI Switch, one of which is
20 that the Auto IMSI Switch SIM application is able to detect rejection of user
equipment’s in attempting to attach to the available network followed by the
second prerequisite that the SIM application is able to affirm that the user
equipment is in the international location.
Additionally, for efficient swapping of the IMSI, the user equipment should be
25 able to communicate with the subscriber identity module using a variety of
commands such as proactive commands (as specified in the 3GPP TS 31.111
standard, including, but not limiting to, SET UP EVENT LIST and REFRESH) and the
ENVELOPE commands (as specified in the 3GPP TS 31.111 standard, including,
4
but not limiting to, Event Download). Further, in situations where the attach
request of the user equipment cannot be accepted by the international roaming
network, the international roaming network rejects the attach request based on
appropriate cause code value specified in the 3GPP TS 24.301, including, but not
limiting to, Illegal 5 user equipment, unavailability of cells in tracking area, nonallowable
EPS service, non‐allowable tracking area and non‐allowable PLMN. The
existing technologies for Auto IMSI Switch SIM application provide a solution by
using a particular Elementary File (EF) of the SIM card viz. EFFPLMN. When the user
equipment having the home IMSI sends the attach request to the international
10 roaming network and receives an attach reject with reject Cause such as “PLMN
Not Allowed”, the user equipment updates the Forbidden PLMN list in the USIM
FPLMN elementary file (EFFPLMN) with the PLMN value of the roamed network
from which it received the reject message resulting in triggering of the Auto IMSI
Switch SIM application to replace the home IMSI by global IMSI. Thereupon,
15 when the user equipment having the global IMSI re‐sends the attach request, the
international roaming network will be attached successfully with the user
equipment. Similarly, the Auto IMSI Switch SIM application can be triggered
when the user returns back to the home network from the international
roaming. However, these existing solutions for Auto IMSI Switch SIM application
20 poses certain limitations, one of which is inability to update the EFFPLMN values
when the reject cause is not “PLMN Not Allowed” i.e. in the event the reject
cause is not “PLMN Not Allowed”, the Auto IMSI Switch SIM application cannot
be triggered. Thus, this Auto IMSI Switch SIM application is not a robust criteria.
Another limitation relates to a limited amount of memory and processing power
25 available on the SIM card. In an exemplary event, different user equipments
update the EFFPLMN differently based on their implementation since there is no
standard definition to update the FPLMN list. Therefore, this approach is less
efficient and poses certain limitations, inter alia, the Auto IMSI Switch SIM
5
application compares the updated values with the previous values to detect the
updation.
Accordingly, in order to overcome the aforementioned problems inherent in the
existing solutions for Auto IMSI Switch SIM application, there exists a need of an
efficient mechanism to create 5 holistic criteria for Auto IMSI Switch SIM
application independent of the cause code sent by any operator and can work
regardless of the cause code received.
SUMMARY
This section is provided to introduce certain objects and aspects of the present
10 disclosure in a simplified form that are further described below in the detailed
description. This summary is not intended to identify the key features or the
scope of the claimed subject matter.
Embodiments of the present disclosure relate to a method for availing at least
one service by a user equipment while in an international roaming, the method
15 comprising: transmitting , by the user equipment, an attach request to at least
one second network in an event the user equipment having a home IMSI is in the
international roaming by entering a second location from a first location,
wherein the first location is served by at least one first network and the second
location is served by the at least one second network, and the home IMSI
20 corresponds to the first location; receiving, by the user equipment, an attach
reject in response to the attach request, wherein the attach reject is received
from the at least one second network; notifying, by the user equipment, the
attach reject to a subscriber identity module configured in the user equipment;
determining , by the subscriber identity module, at least one network parameter
25 of the at least second network, wherein the at least one network parameter
comprises a mobile country code of the second location; replacing the home
IMSI with a global IMSI, by the subscriber identity module, in an event the at
6
least one network parameter corresponds to the second location; retransmitting,
by the user equipment having the global IMSI, the attach request to
the at least one second network; and availing, by the user equipment, the at
least one service while in the international roaming in an event the at least one
second network 5 accepts the attach request with the global IMSI.
Further, the embodiments of the present disclosure encompass a method for
availing at least one service by a user equipment while leaving an international
roaming, the method comprising: transmitting, by the user equipment, an attach
request to at least one first network in an event the user equipment having a
10 global IMSI leaves the international roaming by entering a first location from a
second location, wherein the first location is served by at least one first network
and the second location is served by the at least one second network; receiving,
by the user equipment, an attach reject in response to the attach request from
the at least one first network, wherein the attach reject is received from the at
15 least one first network; notifying, by the user equipment, the attach reject to a
subscriber identity module configured in the user equipment; determining, by
the subscriber identity module, at least one network parameter of the at least
first network, wherein the at least one network parameter comprises a mobile
country code of the first location; replacing the global IMSI with a home IMSI by
20 the subscriber identity module, in an event the at least one network parameter
corresponds to the first location; re‐transmitting, by the user equipment having
the home IMSI, the attach request to the at least one first network; and availing
the at least one service by the user equipment while leaving the international
roaming in an event the at least one first network accepts the attach request
25 with the home IMSI.
Moreover, the embodiments of the present disclosure encompass a system for
availing at least one service by a user equipment while one of in an international
roaming and leaving the international roaming, the system comprising: a user
7
equipment configured to: transmit an attach request to at least one second
network in an event the user equipment having a home IMSI is in the
international roaming by entering a second location from a first location, and
transmit an attach request to at least one first network in an event the user
equipment having a global IMSI 5 leaves the international roaming by entering the
first location from the second location, wherein the first location is served by at
least one first network and the second location is served by the at least one
second network, and the home IMSI corresponds to the first location; receive an
attach reject in response to the attach request from one of the at least one first
10 network and the at least one second network; notify the attach reject to a
subscriber identity module configured in the user equipment; and the subscriber
identity module configured to: determine at least one network parameter of one
of the at least one first network and the at least one second network, wherein
the at least one network parameter of the at least one first network and the at
15 least one second network comprises a mobile country code of the first location
and the second location, respectively; replace the home IMSI of the user
equipment with the global IMSI in an event the at least one network parameter
corresponds to the second location; replace the global IMSI of the user
equipment with the home IMSI in an event the at least one network parameter
20 corresponds to the first location; wherein, the user equipment having one of the
home IMSI and the global IMSI is configured to re‐transmit the attach request to
one of the at least one first network and the at least one second network to avail
the at least one service while one of in the international roaming and leaving the
international roaming in an event the at least one first network and the at least
25 one second network accepts the home IMSI and the global IMSI, respectively.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated herein, and constitute a
part of this disclosure, illustrate exemplary embodiments of the disclosed
8
methods and systems in which like reference numerals refer to the same parts
throughout the different drawings. Components in the drawings are not
necessarily to scale, emphasis instead being placed upon clearly illustrating the
principles of the present disclosure. Some drawings may indicate the
components using block 5 diagrams and may not represent the internal circuitry of
each component. It will be appreciated by those skilled in the art that disclosure
of such drawings includes disclosure of electrical components or circuitry
commonly used to implement such components.
FIG.1 illustrates a system architecture [100] for availing at least one service by a
10 user equipment while one of in an international roaming and leaving the
international roaming in accordance with an embodiment of the present
disclosure.
FIG.2 illustrates an exemplary method flow diagram [200] comprising the
method for availing at least one service by a user equipment while in an
15 international roaming in accordance with an embodiment of the present
disclosure.
FIG.3 illustrates an exemplary method flow diagram [300] comprising the
method for availing at least one service by a user equipment while leaving an
international roaming in accordance with an embodiment of the present
20 disclosure.
DETAILED DESCRIPTION
In the following description, for the purposes of explanation, various specific
details are set forth in order to provide a thorough understanding of
embodiments of the present disclosure. It will be apparent, however, that
25 embodiments of the present disclosure may be practiced without these specific
details. Several features described hereafter can each be used independently of
one another or with any combination of other features. An individual feature
9
may not address any of the problems discussed above or might address only one
of the problems discussed above. Some of the problems discussed above might
not be fully addressed by any of the features described herein. Example
embodiments of the present disclosure are described below, as illustrated in
various drawings in which like 5 reference numerals refer to the same parts
throughout the different drawings.
Embodiments of the present disclosure may relate to a system and methods for
availing a service by a user equipment when user is either in an international
roaming or is leaving the international roaming. The system comprises a user
10 equipment and a subscriber identity module configured inside the user
equipment for providing functionalities in accordance with the present
invention. Further, the user equipment, present within a first network,
communicates with a second network for availing services when the user
equipment is in international roaming, provided the second network may have
15 the bilateral agreement with the service provider of the subscriber identity
module. Similarly, the user equipment, present within the second network,
communicates with the first network for availing services when the user
equipment leaves international roaming. Furthermore, the user equipment may
have more than one or two subscriber identity modules configured to operate
20 either one at a time or all at the same.
The at least one service as used herein may comprise at least one of a voice call,
multimedia broadcast multicast message, a voice message, a short message
service, a VoIP data, a video data and internet data.
The user equipment as used herein may refer to any computing device operable
25 with a subscriber identity module (SIM), wherein the subscriber identity module
comprises an IMSI, a unique key shared with the network operator. The user
equipment present in a home location may have a home IMSI, while the user
equipment present in an international location (second location) may have a
10
global IMSI. Further, the user equipment includes, but not limited to, a smart
phone, a mobile phone, a tablet, a phablet and any such device as obvious to a
person skilled in the art. Furthermore, the user equipment may comprise an
input means such as a keyboard, an operating system, a memory unit, a display
interface, 5 etc. which functions/communicates with other entities such as base
station or any such network equipment with the help of the subscriber identity
module.
The first location as used herein may refer to the home location of the subscriber
identity module, wherein the first location is served by at least one first network
10 i.e. the at least one first network provide the at least one service to the user
equipment located in the home location.
The second location as used herein may refer to any international location other
than the home location of the subscriber identity module, wherein the second
location is served by at least one second network i.e. the at least one second
15 network i.e. the at least one second network provide the at least one service to
the user equipment located in the second location
The international roaming as used herein may refer to any event when the user
equipment avails services while travelling outside the geographical coverage
area of the home location.
20 FIG.1 illustrates a preferred embodiment of the present disclosure which
encompasses a system architecture for availing at least one service by a user
equipment when user is either in an international roaming or is leaving the
international roaming. The system [100] comprises a user equipment [110] and a
subscriber identity module [120] configured inside the user equipment for
25 providing various functionalities in accordance with the present invention.
As illustrated in the FIG. 1, the user equipment [110] comprises a plurality of sub
systems [102, 102A, 120B, 102C, 103, 104, 105 and 106].
11
In an event, the user having the user equipment [110] enters into the
international roaming when travels from the first location to the second location,
the user equipment [110] may not be able to avail any services since the IMSI of
the subscriber identity module remains home IMSI, since user equipment having
the home IMSI may not 5 be permitted to avail services from the second location.
The user equipment [110] having the home IMSI may further be configured to
scan the at least one second network available in the second location to transmit
an attach request to the at least one second network, wherein the attach
request comprises either the home IMSI or the global IMSI. The attach request
10 comprises the home IMSI in an event the user equipment [110] travels from the
first location to the second location.
The user equipment [110] may further receive an attach reject in response to the
attach request from the at least one second network in an event the home
network operator may not have the bilateral roaming agreement with the
15 network operator in the international location into which the subscriber is
roaming. The attach reject comprises one of a location update reject message, a
GPRS attach reject message, a routing area update reject message and a tracking
area update message.
On receiving the attach reject, the user equipment [110] may be configured to
20 notify the attach reject to the subscriber identity module [120], thereby
triggering the auto IMSI Switch SIM application. In a preferred embodiment, the
user equipment [110] may notify an event data to the subscriber identity module
[120], wherein the event data comprises one of a location information data, a
routing area identification data and a tracking area identification data. The
25 subscriber identity module [120] may further determine at least one network
parameter of the at least second network, wherein the at least one network
parameter includes a mobile country code of the second location, but not limited
to, a network code, a routing area code and a location area code. In a preferred
12
embodiment, the subscriber identity module [120] may determine the at least
one network parameter of the at least second network based on the Auto IMSI
switch SIM application residing in the subscriber identity module [120]. Further,
the subscriber identity module [120] may replace the home IMSI with the global
IMSI based on at least one of the information 5 related to the home IMSI and the
global IMSI in the Auto IMSI Switch SIM application, the at least one second
network and the at least one first network in an event the at least one network
parameter corresponds to the second location. The present invention therefore,
encompasses replacing of the home IMSI with the global IMSI, irrespective of the
10 cause code sent by the user.
Further, the user equipment [110] having the global IMSI may be configured to
re‐scan the at least one second network available in the second location to
transmit an attach request to the at least one second network, wherein the
attach request will now comprise the global IMSI of the user equipment [110]. In
15 an event any one of the at least one second network operator has the bilateral
roaming agreement with the network operator in the international location into
which the subscriber is roaming, the at least one second network accepts the
new attach attempt of the user equipment [110], the user equipment [110] may
be enabled to avail the at least one service while in the international roaming. In
20 another embodiment, when the user having the user equipment [110] travels
further to a new location other than the home location, the user equipment
[110] having the global IMSI may be served by a set of new networks (other than
the at least one first network) subject to the bilateral agreement between the
home and the roamed network operators.
25 Similarly, in another instance, the user having the user equipment [110] with the
global IMSI leaves the international roaming, when travels back to the first
location from the second location, the user equipment [110] having the global
IMSI may further be configured to scan at least one first network available in the
13
first location to transmit an attach request to the at least one first network,
wherein the attach request comprises the global IMSI. The user equipment [110]
may further receive an attach reject in response to the attach request from the
at least one first network in an event the global IMSI is not switched back to the
home IMSI, wherein the attach 5 reject comprises one of the location update
reject message, the GPRS attach reject message, the routing area update reject
message and the tracking area update message. Further, on receiving the attach
reject, the user equipment [110] may be configured to notify the attach reject to
the subscriber identity module [120], thereby triggering the auto IMSI Switch
10 SIM application. In a preferred embodiment, the user equipment [110] may
notify the event data to the subscriber identity module [120], wherein the event
data comprises one of a location information data, a routing area identification
data and a tracking area identification data.
The subscriber identity module [120] may further determine at least one
15 network parameter of the at least first network, wherein the at least one
network parameter includes a mobile country code of the first location, but not
limited to, the network code, the routing area code and the location area code.
In a preferred embodiment, the subscriber identity module [120] may determine
the at least one network parameter of the at least first network based on the
20 Auto IMSI switch SIM application residing in the subscriber identity module
[120].
Further, the subscriber identity module [120] may replace the global IMSI with
the home IMSI based on at least one of the information related to the home IMSI
and the global IMSI in the Auto IMSI Switch SIM application, the at least one
25 second network and the at least one first network in an event the at least one
network parameter corresponds to the first location. The present invention
therefore, encompasses replacing of the global IMSI with the home IMSI,
irrespective of the cause code sent by the user.
14
Further, the user equipment [110] having the home IMSI may be configured to
re‐scan the at least one first network available in the first location to transmit an
attach request to the at least one first network, wherein the attach request will
now comprise the home IMSI of the user equipment [110]. Consequently, the
user equipment [110] may be enabled 5 to avail the at least one service while
leaving the international roaming in an event any one of the at least one first
network international network accepts the new attach attempt of the user
equipment [110] having the home IMSI.
Further, the subsystems [102, 102A, 120B, 102C, 103, 104, 105 and 106]
10 comprised within the user equipment [110] may include, but not limiting to, a
modem subsystem [102] with a Baseband DSP processor [102C] and a plurality of
radio interfaces [102A]. The user equipment [110] may further include a cellular
radio [102B] transmission/reception radio frequency (RF) connected to the
antenna [107] for receiving and transmitting wireless services such as VoIP and
15 Internet/Intranet services. Also, the user equipment [110] may comprise an
application processor [104], a memory subsystem [105], a power subsystem
[106] and an external I/O interfaces subsystem [103].
The subscriber identity module [120] comprises a processor [120B], an I/O
interface [120A], a RAM temporary storage [120C], an EEPROM / Non‐ volatile
20 Memory (NVM) [120D] and a SIM file system [120E]. Further, the EEPROM / Non‐
Volatile Memory (NVM) [120D] consists of an operating system code, a code of
other SIM applications and the Auto IMSI Switch SIM application. The SIM file
system [120E] and USIM application contains EF files such as EFLOCI, EFPSLOCI,
EFEPSLOCI, EFUST, EFFPLMN, etc., various application specific files used by SIM
25 applications running on the subscriber identity module [120] and a plurality of
context and configuration files of the Auto IMSI Switch SIM application. The
present invention encompasses storage of information related to the home IMSI
and the global IMSI in the Auto IMSI Switch SIM application.
15
As illustrated in FIG. 2, the present disclosure encompasses an exemplary
method [200] for availing at least one service by a user equipment while in an
international roaming in accordance with an embodiment of the present
disclosure, wherein the method may be performed by the user equipment [110]
and the subscriber identity 5 module [120]. The following includes detailed steps
involved in availing at least one service by a user equipment in an international
roaming. The method [200] may initiate at step 202 where the user having the
user equipment [110] with the home IMSI travels from the first location to the
second location while entering the international roaming. The user having the
10 user equipment [110] enters into the international roaming when travels from
the first location to the second location, and may not be able to avail any
services since the IMSI of the subscriber identity module remains home IMSI.
At step 204, the user equipment [110] having the home IMSI may be configured
to scan the at least one second network available in the second location.
15 At step 206 and after the accomplishment of the step 204, the user equipment
[110] may transmit an attach request to the at least one second network,
wherein the attach request comprises the home IMSI in this event where the
user equipment [110] travels from the first location to the second location.
At step 208, the user equipment [110] may receive an attach reject in response
20 to the attach request from the at least one second network in an event the home
network operator may not have the bilateral roaming agreement with the
network operator in the international location. The attach reject comprises one
of the location update reject message, the GPRS attach reject message, the
routing area update reject message and the tracking area update message.
25 At step 210, the user equipment [110], on receiving the attach reject, may be
configured to notify the attach reject to the subscriber identity module [120],
thereby triggering the auto IMSI Switch SIM application. In a preferred
16
embodiment, the user equipment [110] may notify the event data to the
subscriber identity module [120], wherein the event data comprises one of the
location information data, the routing area identification data and the tracking
area identification data.
At step 212, the subscriber identity 5 module [120] may determine the at least one
network parameter of the at least second network wherein the at least one
network parameter includes the mobile country code of the second location, but
not limited to, the network code, the routing area code and the location area
code. In a preferred embodiment, the subscriber identity module [120] may
10 determine the at least one network parameter of the at least second network
based on the Auto IMSI switch SIM application residing in the subscriber identity
module [120].
At step 214, the subscriber identity module [120] may check whether or not the
at least one network parameter of the at least second network correspond to the
15 second location. In an event the at least one network parameter corresponds to
the second location, the method [200] may lead to step 216. Alternately, the
method [200] may terminate at the step 222.
At step 216, the subscriber identity module [120] may replace the home IMSI
with the global IMSI based on at least one of the information related to the
20 home IMSI and the global IMSI in the Auto IMSI Switch SIM application, the at
least one second network and the at least one first network.
At step 218, the user equipment [110] having the global IMSI may be configured
to re‐scan the at least one second network available in the second location to
transmit an attach request to the at least one second network, wherein the
25 attach request will now comprise the global IMSI of the user equipment [110].
At step 220, the user equipment [110] may avail the at least one service while in
the international roaming in an event any one of the at least one second network
17
operator has the bilateral roaming agreement with the network operator in the
international location into which the subscriber is roaming and accepts the new
attach attempt of the user equipment [110. In another embodiment, when the
user having the user equipment [110] travels further to a new location other
than the home location, the 5 user equipment [110] having the global IMSI may be
served by a set of new networks (other than the at least one first network)
subject to the bilateral agreement between the home and the roamed network
operators. The method [200] terminates at the step 222.
As illustrated in FIG. 3, the present disclosure encompasses an exemplary
10 method [300] for availing at least one service by the user equipment while
leaving an international roaming in accordance with an embodiment of the
present disclosure, wherein the method may be performed by the user
equipment [110] and the subscriber identity module [120]. The following
includes detailed steps involved in availing at least one service by the user
15 equipment while leaving the international roaming. The method [300] may
initiate at step 302 where the user having the user equipment [110] with the
global IMSI travels back to the first location from the second location while
leaving the international roaming. The user having the user equipment [110]
leaves the international roaming when travels from the second location to the
20 first location, and may not be able to avail any services since the IMSI of the
subscriber identity module remains global IMSI.
At step 304, the user equipment [110] having the global IMSI may be configured
to scan the at least one first network available in the first location.
At step 306 and after the accomplishment of the step 304, the user equipment
25 [110] may transmit an attach request to the at least one first network, wherein
the attach request comprises the global IMSI in this event where the user
equipment [110] travels from the second location to the first location.
18
At step 308, the user equipment [110] may receive an attach reject in response
to the attach request from the at least one first network in an event the global
IMSI is not switched back to the home IMSI. The attach reject comprises one of a
location update reject message, the GPRS attach reject message, the routing
area 5 update reject message and the tracking area update message.
At step 310, the user equipment [110], on receiving the attach reject, may be
configured to notify the attach reject to the subscriber identity module [120],
thereby triggering the auto IMSI Switch SIM application. In a preferred
embodiment, the user equipment [110] may notify the event data to the
10 subscriber identity module [120], wherein the event data comprises one of the
location information data, the routing area identification data and the tracking
area identification data.
At step 312, the subscriber identity module [120] may determine the at least one
network parameter of the at least first network , wherein the at least one
15 network parameter includes a mobile country code of the second location, but
not limited to, the network code, the routing area code and the location area
code. In a preferred embodiment, the subscriber identity module [120] may
determine the at least one network parameter of the at least first network based
on the Auto IMSI switch SIM application residing in the subscriber identity
20 module [120].
At step 314, the subscriber identity module [120] may check whether or not the
at least one network parameter corresponds to the first location. In an event the
at least one network parameter corresponds to the first location, the method
[300] may lead to step 316. Alternately, the method [300] may terminate at the
25 step 322.
At step 316, the subscriber identity module [120] may replace the global IMSI
with the home IMSI based on at least one of the information related to the home
19
IMSI and the global IMSI in the Auto IMSI Switch SIM application, the at least one
second network and the at least one first network.
At step 318, the user equipment [110] having the home IMSI may now be
configured to re‐scan the at least one first network available in the first location
to transmit the attach request 5 to the at least one first network, wherein the
attach request will now comprise the home IMSI of the user equipment [110].
At step 320, the user equipment [110] may avail the at least one service while
leaving the international roaming in an event any one of the at least one first
network International network accepts the new attach attempt of the user
10 equipment [110] having the home IMSI. The method [300] terminates at the step
322.
Therefore, the present invention encompasses a system and methods for
availing the services by the user equipment when the user is either in the
international roaming or is leaving the international roaming. The present
15 invention further encompasses replacing of the home IMSI with the global IMSI
and vice versa, irrespective of the cause code sent by the user, thereby providing
a robust solution in any international roaming scenario covering all the rejection
cause codes of the user equipment’s attach attempt. This in turn helps in
reducing the probability of the failure of providing service to the users in the
20 international locations.
Though a limited number of the user equipment [110], the subscriber identity
module [120] and the components/sub systems therein, have been shown in the
figures; however, it will be appreciated by those skilled in the art that the system
[100] of the present disclosure encompasses any number and varied types of the
25 entities/elements user equipment [110], the subscriber identity module [120]
and the components/sub systems therein.
20
While considerable emphasis has been placed herein on the disclosed
embodiments, it will be appreciated that many embodiments can be made and
that many changes can be made to the embodiments without departing from the
principles of the present disclosure. These and other changes in the
embodiments of the present 5 disclosure will be apparent to those skilled in the
art, whereby it is to be understood that the foregoing descriptive matter to be
implemented is illustrative and non‐limiting.
21
We claim:
1. A method [200] for availing at least one service by a user equipment [110]
while in an international roaming, the method [200] comprising:
 transmitting, by the user equipment [110], an attach request to at
least one second 5 network in an event the user equipment [110]
having a home IMSI is in the international roaming by entering a
second location from a first location, wherein
the first location is served by at least one first network and the
second location is served by the at least one second network, and
10 the home IMSI corresponds to the first location;
 receiving, by the user equipment [110], an attach reject in response
to the attach request, wherein the attach reject is received from the
at least one second network;
 notifying, by the user equipment [110], the attach reject to a
15 subscriber identity module [120] configured in the user equipment;
 determining, by the subscriber identity module [120], at least one
network parameter of the at least second network, wherein the at
least one network parameter comprises a mobile country code of the
second location;
20  replacing the home IMSI with a global IMSI, by the subscriber identity
module [120], in an event the at least one network parameter
corresponds to the second location;
 re‐transmitting, by the user equipment [110] having the global IMSI,
the attach request to the at least one second network; and
25  availing, by the user equipment, the at least one service while in the
international roaming in an event the at least one second network
accepts the attach request with the global IMSI.
22
2. The method [200] as claimed in claim 1, further comprising notifying an
event data to the subscriber identity module, wherein the event data
comprises one of a location information data, a routing area identification
data and a tracking area identification data.
3. The method [200] as claimed 5 in claim 1, wherein the at least one service
comprises at least one of a voice call, a multimedia broadcast multicast
message, a voice message, a short message service, a VoIP data, a video data
and internet data.
4. The method [200] as claimed in claim 1, wherein the attach request
10 comprises one of the home IMSI and the global IMSI.
5. The method [200] as claimed in claim 1, wherein the first location
corresponds to a home location of the subscriber identity module.
6. The method [200] as claimed in claim 1, wherein the second location
corresponds to a location other than the home location of the subscriber
15 identity module.
7. The method [200] as claimed in claim 1, wherein the attach reject comprises
one of a location update reject message, a GPRS attach reject message, a
routing area update reject message and a tracking area update message.
8. The method [200] as claimed in claim 1, wherein the at least one network
20 parameter of the at least second network further comprises at least one of a
mobile network code, a routing area code and a location area code.
9. A method [300] for availing at least one service by a user equipment [110]
while leaving an international roaming, the method [300] comprising:
 transmitting, by the user equipment, an attach request to at least one
25 first network in an event the user equipment [110] having a global
23
IMSI leaves the international roaming by entering a first location from
a second location, wherein
the first location is served by at least one first network and the
second location is served by the at least one second network;
 receiving, by the user 5 equipment, an attach reject in response to the
attach request from the at least one first network, wherein the attach
reject is received from the at least one first network;
 notifying, by the user equipment, the attach reject to a subscriber
identity module [120] configured in the user equipment;
10  determining, by the subscriber identity module, at least one network
parameter of the at least first network, wherein the at least one
network parameter comprises a mobile country code of the first
location;
 replacing the global IMSI with a home IMSI by the subscriber identity
15 module, in an event the at least one network parameter corresponds
to the first location;
 re‐transmitting, by the user equipment [110]having the home IMSI,
the attach request to the at least one first network; and
 availing the at least one service by the user equipment [110] while
20 leaving the international roaming in an event the at least one first
network accepts the attach request with the home IMSI.
10. The method [300] as claimed in claim 9, further comprising notifying an
event data at a subscriber identity module [120] configured in the user
equipment, wherein the event data comprises one of a location information
25 data, a routing area identification data and tracking area identification data.
11. The method [300] as claimed in claim 9, wherein the at least one network
parameter of the at least first network further comprises at least one of a
mobile network code, a routing area code and a location area code.
24
12. A system [100] for availing at least one service by a user equipment [110]
while one of in an international roaming and leaving the international
roaming, the system [100] comprising:
 a user equipment [110] configured to:
transmit an attach request 5 to at least one second network in an
event the user equipment [110] having a home IMSI is in the
international roaming by entering a second location from a first
location, and
transmit an attach request to at least one first network in an
10 event the user equipment [110] having a global IMSI leaves the
international roaming by entering the first location from the
second location, wherein
the first location is served by at least one first network and
the second location is served by the at least one second
15 network, and
the home IMSI corresponds to the first location;
receive an attach reject in response to the attach request from
one of the at least one first network and the at least one second
network;
20 notify the attach reject to a subscriber identity module [120]
configured in the user equipment; and
 the subscriber identity module [120] configured to:
determine at least one network parameter of one of the at least
one first network and the at least one second network, wherein
25 the at least one network parameter of the at least one first
network and the at least one second network comprises a mobile
25
country code of the first location and the second location,
respectively;
replace the home IMSI of the user equipment [110] with the
global IMSI in an event the at least one network parameter
5 corresponds to the second location;
replace the global IMSI of the user equipment [110] with the
home IMSI in an event the at least one network parameter
corresponds to the first location;
wherein, the user equipment [110] having one of the home IMSI and the
10 global IMSI is configured to re‐transmit the attach request to one of the
at least one first network and the at least one second network to avail the
at least one service while one of in the international roaming and leaving
the international roaming in an event the at least one first network and
the at least one second network accepts the home IMSI and the global
15 IMSI, respectively.
13. The system [100] as claimed in claim 12, wherein the user equipment [110] is
further configured to notify an event data to the at least one subscriber
identity module, wherein the event data comprises one of a location